Antoine Boutros - In 1969, the Swiss Biochemist Friedrich Miescher succeeded in isolating an enigmatic chemical substance in the nucleus of the cell. Heedless of that substance’s significance, Miescher did not complete his research and the substance remained in the shadow alongside several discoveries waiting to be brought to light.

It wasn’t until after half a century that researchers realized that the said substance, known today as the Deoxyribonucleic Acid or DNA, is the core of living organisms and consequently the material on which life is built as well as the active agent of heredity. However, the exact position of the gene on the chromosome wasn’t specified until 1968.

The long term Mendelian results remained unveiled for a long time and there was no such science as genetics when they were discovered. All that was known at the time was that the gene is responsible for passing inherited traits from one generation to the next.

Science reached a major milestone in genetics in the year 1915 following experiments conducted at Columbia University by scientist Thomas Morgan with a fruit fly known as Drosophila Melanogaster. The fly was chosen for the experiment thanks to the large size of its chromosomes which can easily be seen under microscope in bead-like structures. Morgan and his team were able to identify the location of the genes on the fruit-fly chromosomes. In 1915, he and his colleagues joined hands to publish “The Mechanism of Mendelian Heredity”, the first book to provide a solid and thorough explanation for Mendel’s laws. However, the mysteries surrounding the tangible and physical nature of the gene were yet to be unfolded.

In 1917, American scientist Sewall Wright came a long way in understanding the gene structure and realized that the gene is responsible for controlling the reactions of enzymes (proteins that catalyze biochemical reactions in the body) although science could not isolate any enzyme until the year 1926.

At that time people believed that the gene is made up of proteins and amino acids and that the latter are of minor importance. However, a series of intriguing experiments held by Oswald Avery in Rockefeller Institute in the early forties of last century propelled scientists to realize that gene activity is influenced primarily by amino acids rather than proteins.

The discovery came contrary to all expectations and even Avery exhibited hesitation in accepting the new findings. Eight years later, Alfred Hershey and his assistant Martha Chase noticed that when viral DNA penetrates bacteria, it cancels their genetic information and imposes its own, thus putting an indisputable end to the controversy.

Another milestone was achieved in the early fifties when molecular biology swept over by leaps and bounds and seemed reliable, unlike its antecedents, in unfolding life mysteries and providing biology with new approaches for research and interpretation. Back then, scientists did not restrict themselves to determining the hereditary role of the gene but embarked on the tiresome mission of identifying the molecular structure that explains hereditary mechanisms and molecular biology supplied them with all the means necessary.

A team of scientists presided by British Biophysicist Maurice Wilkins initiated a research aiming at identifying the DNA composition in order to figure out its operation mode. The team believed that the secret of life must present an opportunity to clone or recopy the cell. The team used X-ray Crystallography, a 1938 technique in which a beam of X-ray strikes a crystal from different angles producing reflecting patterns that land on a detector to expose its geometric structure and internal composition.

Although Wilkins concluded that the DAN resembles a braided rope, he failed to provide answers with regard to the method in which it makes identical copies that allow the transmission of genetic material from one cell to the next. It is noteworthy to mention that this historical achievement was a feather in the cap of two obscure scientists unfitted for such a great discovery.

(To be continued)